In the Christmas issue of the New Yorker, I published a response to Peter Schjeldahl's excellent article on the restoration of the Ghent Altarpiece, the monumental painted triptych that Jan van Eyck finished in 1432, and which is currently on display in the Ghent cathedral it was created to adorn, Saint Bavo. The altarpiece is considered to be the first major painting of the Renaissance, a forerunner of Realism, and the first great oil painting. For these art historical firsts and many others, this altarpiece — which is also referred to by the subject of its central panel, "The Adoration of the Mystic Lamb" — is widely considered to be the single most influential painting ever made.

Schjeldahl's article, which appeared in November, clearly describes the debate in the art world about the extent of the work's conservation, how invasive and dramatic the interventions should be — a discussion first highlighted during the 1980-84 Sistine Chapel restoration and now brought to the fore by this no-less influential artwork. But in addition to the importance of the Ghent Altarpiece to the history of art, there is another side to its story that is of interest, and one that is directly relevant to Schjeldahl's article. For the Ghent Altarpiece is also the most frequently stolen artwork in history.

Jan van Eyck's monumental triptych has been the object of thirteen different crimes over 600 years, including seven separate thefts. It was hunted by Napoleon, Hitler, and Göring — the Nazis wanted it to be the centerpiece of Hitler's planned "supermuseum" at Linz — and the altarpiece, or panels of it, were stolen with such frequency that the painting has not remained entirely intact for more than a few decades. But the most relevant theft to the story of the restoration of the Ghent Altarpiece came in 1934.

That year a single two-sided panel, depicting the so-called "Righteous Judges" (the panel on the bottom left corner when the altarpiece is open) was stolen from the cathedral of Saint Bavo. After months of frankly bizarre ransom negotiations, and the return of the back of the two-sided panel (the side depicting St. John the Baptist), the police closed the case. The case had been riddled with police incompetence and odd decisions that smacked to many of conspiracy — there were even whispers that members of the cathedral were involved in the theft and attempted ransom. (This complex theory is one subject I investigate in my new book "Stealing the Mystic Lamb: The True Story of the World's Most Coveted Masterpiece.") In 1945 a Belgian conservator called Jef van der Veken painted an identical replacement copy of the "Righteous Judges" and, since the theft remained unsolved and the original "Judges" panel was missing, the Belgian government installed the van der Veken copy in the original altarpiece in 1950. Therefore, what we see when we visit the Ghent Altarpiece is 11 out of 12 original panels, plus the replacement copy.

The coda to this story is intriguing, and offers up a mystery that the Getty Conservation effort will solve. In 1974, after years of cleaning the altarpiece, conservator Jos Trotteyn showed up for work and did a double-take. Suddenly he could have sworn that the "Judges" panel had aged several centuries since his last visit. It now had the craquelure and patina of age — and he thought he could see pentimenti, under-drawing, ghosting through the surface of the paint. His theory was that the thieves of the original "Judges" panel had chosen to surreptitiously return the stolen panel to the altarpiece, by having the then-deceased van der Veken paint over the stolen original. The thin top layer of paint had faded after thirty years, so the pentimenti that Trotteyn now saw was in fact van Eyck's original, peaking out from beneath.

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This suspicion was perhaps encouraged by the fact that van der Veken had written an odd rhyming quattrain in Flemish on the back of his replacement panel, which translates roughly as: "I did it for love/And for duty/And for vengeance/Sly strokes have not disappeared." Van der Veken refused to explain this quattrain —  he was also thought by some to be an art forger, in addition to his role as the leading conservator of the Musee des Beaux-Arts in Brussels. (In 2004 a monograph exhibition called "Fake or Not Fake" at the Groeninge Museum in Bruges considered Van der Veken's often heavy-handed restoration efforts, which in cases veered toward forgery.)

The officials of Saint Bavo took Trotteyn's suggestion seriously, and submited the panel to testing. Unfortunately, they later said, this is the copy, not the missing original. But they refused to release the results of their study, and put off journalists who inquired, suggesting to some a cover-up. If members of Saint Bavo had been involved in the 1934 theft, then perhaps there was reason for this secrecy?

But the mystery can now be solved and revealed here, officially, for the first time. The Getty conservators have tested the "Judges" panel and concur with the previous report — this is, indeed, the van der Veken copy.

This means that the stolen original is still out there. The best theories as to its location suggest that it was moved and hidden on the premises of Saint Bavo Cathedral. Government-sponsored treasure hunts have sought it, but found nothing. The missing panel remains missing.

ARTINFO is proud to welcome Noah Charney's new blog The Secret History of Art to our roster of contributors. Charney is a professor of art history at the American University of Rome, the president of the Association for Research Into Crimes Against Art, and the best-selling author of "Stealing the Mystic Lamb" and other books.